Chronic pulmonary infection and associated airway obstruction are major factors in the pathophysiology of cystic fibrosis (CF). Previous work in this laboratory demonstrated the presence of an activity in CF serum which specifically inhibits phagocytosis of Pseudomonas (PA) by both CF and normal human alveolar macrophages (AM). Ultrastructure studies indicate no morphological evidence of in vivo bacterial phagocytosis by CF macrophages. This project is designed to extend these findings by correlating in vitro observations with the assessment of the in vivo status as a function of the stage of the disease. To achieve this objective, lung cells from CF patients in various stages of the disease will be studied together with the milieu in which these cells exist. The ability of alveolar macrophages and PMNs to phagocytize and kill bacteria will be studied and the effect of lung lavage fluid on these processes will be evaluated comparing lavage fluid from CF patients and control subjects. This analysis of the structure and function of the CF lung cell populations and the milieu of these cells is necessary to better characterize the host response to chronic lung colonization by PA. These findings will be correlated with colonization history and clinical status in order to determine if lung cell populations change with increasing age, length of PA colonization, and overall clinical condition. Our access to lung lavage from healthy individuals and patients with CF insures that the primary disease state and infection related alterations can be assessed.